kernel/cpu.c: create a CPU_STARTING cpu_chain notifier

Right now, there is no notifier that is called on a new cpu, before the new
cpu begins processing interrupts/softirqs.
Various kernel function would need that notification, e.g. kvm works around
by calling smp_call_function_single(), rcu polls cpu_online_map.

The patch adds a CPU_STARTING notification. It also adds a helper function
that sends the message to all cpu_chain handlers.

Tested on x86-64.
All other archs are untested. Especially on sparc, I'm not sure if I got
it right.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

14 files changed, 22 insertions, 0 deletions

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 83df541650fc..06b6fdab639f 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -149,6 +149,9 @@ smp_callin(void)
         atomic_inc(&init_mm.mm_count);
         current->active_mm = &init_mm;
 
+        /* inform the notifiers about the new cpu */
+        notify_cpu_starting(cpuid);
+
         /* Must have completely accurate bogos.  */
         local_irq_enable();
 
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index e9842f6767f9..e42a749a56dd 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -277,6 +277,7 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
         /*
          * Enable local interrupts.
          */
+        notify_cpu_starting(cpu);
         local_irq_enable();
         local_fiq_enable();
 
diff --git a/arch/cris/arch-v32/kernel/smp.c b/arch/cris/arch-v32/kernel/smp.c
index 952a24b2f5a9..52e16c6436f9 100644
--- a/arch/cris/arch-v32/kernel/smp.c
+++ b/arch/cris/arch-v32/kernel/smp.c
@@ -178,6 +178,7 @@ void __init smp_callin(void)
         unmask_irq(IPI_INTR_VECT);
         unmask_irq(TIMER0_INTR_VECT);
         preempt_disable();
+        notify_cpu_starting(cpu);
         local_irq_enable();
 
         cpu_set(cpu, cpu_online_map);
diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index bcea81e432fd..333b58f218d0 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -401,6 +401,7 @@ smp_callin (void)
         spin_lock(&vector_lock);
         /* Setup the per cpu irq handling data structures */
         __setup_vector_irq(cpuid);
+        notify_cpu_starting(cpuid);
         cpu_set(cpuid, cpu_online_map);
         per_cpu(cpu_state, cpuid) = CPU_ONLINE;
         spin_unlock(&vector_lock);
diff --git a/arch/m32r/kernel/smpboot.c b/arch/m32r/kernel/smpboot.c
index 2c03ac1d005f..fc2994811f15 100644
--- a/arch/m32r/kernel/smpboot.c
+++ b/arch/m32r/kernel/smpboot.c
@@ -498,6 +498,8 @@ static void __init smp_online(void)
 {
         int cpu_id = smp_processor_id();
 
+        notify_cpu_starting(cpu_id);
+
         local_irq_enable();
 
         /* Get our bogomips. */
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 4410f172b8ab..7b59cfb7e602 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -121,6 +121,8 @@ asmlinkage __cpuinit void start_secondary(void)
         cpu = smp_processor_id();
         cpu_data[cpu].udelay_val = loops_per_jiffy;
 
+        notify_cpu_starting(cpu);
+
         mp_ops->smp_finish();
         set_cpu_sibling_map(cpu);
 
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 5337ca7bb649..c27b10a1bd79 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -453,6 +453,7 @@ int __devinit start_secondary(void *unused)
         secondary_cpu_time_init();
 
         ipi_call_lock();
+        notify_cpu_starting(cpu);
         cpu_set(cpu, cpu_online_map);
         /* Update sibling maps */
         base = cpu_first_thread_in_core(cpu);
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 00b9b4dec5eb..9e8b1f9b8f4d 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -585,6 +585,8 @@ int __cpuinit start_secondary(void *cpuvoid)
         /* Enable pfault pseudo page faults on this cpu. */
         pfault_init();
 
+        /* call cpu notifiers */
+        notify_cpu_starting(smp_processor_id());
         /* Mark this cpu as online */
         spin_lock(&call_lock);
         cpu_set(smp_processor_id(), cpu_online_map);
diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 60c50841143e..001778f9adaf 100644
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -82,6 +82,8 @@ asmlinkage void __cpuinit start_secondary(void)
 
         preempt_disable();
 
+        notify_cpu_starting(smp_processor_id());
+
         local_irq_enable();
 
         calibrate_delay();
diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
index 69596402a500..446767e8f569 100644
--- a/arch/sparc/kernel/sun4d_smp.c
+++ b/arch/sparc/kernel/sun4d_smp.c
@@ -88,6 +88,7 @@ void __init smp4d_callin(void)
         local_flush_cache_all();
         local_flush_tlb_all();
 
+        notify_cpu_starting(cpuid);
         /*
          * Unblock the master CPU _only_ when the scheduler state
          * of all secondary CPUs will be up-to-date, so after
diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
index a14a76ac7f36..9964890dc1db 100644
--- a/arch/sparc/kernel/sun4m_smp.c
+++ b/arch/sparc/kernel/sun4m_smp.c
@@ -71,6 +71,8 @@ void __cpuinit smp4m_callin(void)
         local_flush_cache_all();
         local_flush_tlb_all();
 
+        notify_cpu_starting(cpuid);
+
         /* Get our local ticker going. */
         smp_setup_percpu_timer();
 
diff --git a/arch/um/kernel/smp.c b/arch/um/kernel/smp.c
index be2d50c3aa95..045772142844 100644
--- a/arch/um/kernel/smp.c
+++ b/arch/um/kernel/smp.c
@@ -85,6 +85,7 @@ static int idle_proc(void *cpup)
         while (!cpu_isset(cpu, smp_commenced_mask))
                 cpu_relax();
 
+        notify_cpu_starting(cpu);
         cpu_set(cpu, cpu_online_map);
         default_idle();
         return 0;
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 7985c5b3f916..0b8261c3cac2 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -257,6 +257,7 @@ static void __cpuinit smp_callin(void)
         end_local_APIC_setup();
         map_cpu_to_logical_apicid();
 
+        notify_cpu_starting(cpuid);
         /*
          * Get our bogomips.
          *
diff --git a/arch/x86/mach-voyager/voyager_smp.c b/arch/x86/mach-voyager/voyager_smp.c
index ee0fba092157..199a5f4a873c 100644
--- a/arch/x86/mach-voyager/voyager_smp.c
+++ b/arch/x86/mach-voyager/voyager_smp.c
@@ -448,6 +448,8 @@ static void __init start_secondary(void *unused)
 
         VDEBUG(("VOYAGER SMP: CPU%d, stack at about %p\n", cpuid, &cpuid));
 
+        notify_cpu_starting(cpuid);
+
         /* enable interrupts */
         local_irq_enable();